The long-term objective of this work is to understand the role of the intraflagellar transport (IFT) proteins in vertebrates, with a focus on their role in the primary cilia of kidney and the connecting cilium of photoreceptor cells. In Chlamydomonas and Caenorhabditis elegans these proteins form a multisubunit complex that is transported along flagellar and ciliary microtubules. This transport is essential for assembly and maintenance of cilia and flagella. The IFT particle proteins are conserved in mice and humans. These proteins are found at the connecting cilium in photoreceptor rod cells suggesting that they are important for transport of opsin or other proteins from the cell body to the outer segment. Furthermore, the polycystic kidney disease gene Tg737 encodes the IFT88 subunit of the IFT particle. Mutations in this gene interfere with ciliary assembly in mouse kidneys, suggesting that the primary cilium plays an important role in kidney physiology. The proposed work will determine if the IFT57 and IFT88 proteins are required for intraphotoreceptor transport by examining the effect of mutations on mouse rod cells. The proposed work will also examine the role of IFT57 in formation of kidney primary cilia and will test the hypothesis that the kidney primary cilium is a sensory organelle by determining if osmolarity detectors and somatostatin receptors are localized on primary cilia in the kidney as they are in other cells.